How a Roofing Square Is Calculated
One roofing square covers 100 square feet of actual roof surface, not the footprint of your house. Because roofs are sloped, the surface area is always larger than the floor plan beneath it. A contractor measures the length and width of each roof plane, multiplies them, adds the planes together, then divides by 100 to get the number of squares.
For example, a roof totaling 2,400 square feet of surface area equals 24 squares. Steeper roofs and complex shapes with dormers, valleys, and hips add surface area, so two homes with the same floor size can need very different numbers of squares.
Why Squares Matter for Estimates and Materials
Almost everything on a roof is priced and packaged by the square. Asphalt shingles are sold so that three bundles typically cover one square, and underlayment, drip edge, and labor are all estimated per square. When you compare quotes, the price-per-square is one of the clearest ways to see whether two bids are really measuring the same roof.
- Material orders: Squares tell the crew exactly how many bundles and rolls to deliver.
- Waste factor: Roofers add extra squares for cuts, ridges, and valleys.
- Accurate quotes: A measured square count prevents surprise change orders mid-project.
Why Square Count Matters in the Inland Northwest
In the Spokane and North Idaho climate, the number of squares directly affects how much protection your roof gets against heavy snow, freeze-thaw cycles, ice dams, wind, and hail. Every square needs proper underlayment and, along eaves and valleys, ice-and-water shield to guard against the ice dams that form when snow melts and refreezes at the roof edge.
Steeper Inland Northwest roofs built to shed snow carry more squares than their footprint suggests, which means more material and labor than homeowners often expect. An accurate square count ensures the right amount of weather protection is installed across the entire roof, with no shortcuts in the areas most exposed to our winters. A full roof replacement always starts with measuring your exact square count.
How to Use Squares When Comparing Bids
When you collect estimates, ask each contractor how many squares they measured and what they charge per square. Wildly different square counts usually mean someone measured wrong or is leaving out roof planes. A trustworthy roofer will walk you through the measurement and explain the waste factor they added.
If you want an accurate square count for your home, DG Contracting LLC offers a free estimate with a full roof measurement so you know exactly what your project requires.